1. Field of the Invention
The present invention relates to polyester fibers which are characterized by improved dyeability, and more particularly it relates to novel polyester fibers having a combination of high dyeability with the excellent fiber properties normally possessed by polyethylene terephthalate fibers and to a method for producing the same.
2. Description of the Prior Art
Polyethylene terephthalate fibers have been widely used for various purposes because of their excellent properties, but they have one significant defect in that they are inferior to other fibers in terms of dyeability, which has limited their use for producing cloth materials.
Various methods have been attempted to improve the dyeability of polyethylene terephthalate fibers, e.g., copolymerization, addition of various easily dyeable high molecular weight or low molecular weight materials, physical modification during the production of the fiber step, etc. However, these methods often damage the otherwise excellent mechanical and heat resistant properties of polyethylene terephthalate fibers, and make stable production thereof difficult. They result in increased costs of production which are not offset by the improvements in dyeability. Thus, industrially acceptable methods have not yet been established. Therefore, currently, dyeing of polyethylene terephthalate fibers have been carried out mainly by high pressure dyeing or carrier-dyeing methods.
A need exists therefor, for polyester fibers which are characterized by high dyeability, yet which retain the excellent properties of polyethylene terephthalate fibers.